I have two JBL mpx1200 amps which are making sometimes very loud pop/noise from speakers when turning off. No inputs connected. Otherwise amplifier works perfectly. There is output/speaker relays but they are possibly too slow when turn-off spike appears.
Here is the power input schematic, would it be good idea to put X2 rated capacitor(s) or series RC snubber or MOV accross primary windings AFTER the power switch? There is just one 0.47uF before switch.
Here is the power input schematic, would it be good idea to put X2 rated capacitor(s) or series RC snubber or MOV accross primary windings AFTER the power switch? There is just one 0.47uF before switch.
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Looking at the specs your amps sure have a lot of protection from various fault conditions , do the relays actual function as it says its ON as well as off muting -IE every had any noise on switch on ?
If you pull out the mains plug instead of using the on/off switch does it still produce the same noise ?
If yes then I would agree the time constant to the switch off relay needs to be changed or if a mechanical relay replace the relay (dirty contacts).
If yes then I would agree the time constant to the switch off relay needs to be changed or if a mechanical relay replace the relay (dirty contacts).
update:
there is no noise if power is disconnected by pulling the plug. So it is definitely problem with mains switch installed in wrong position: beetween the capacitor and transformers causing resonant arcing (LC circuit). Im going to change the connection so that mains switch is before filtering PCB, not in the middle of it.
there is no noise if power is disconnected by pulling the plug. So it is definitely problem with mains switch installed in wrong position: beetween the capacitor and transformers causing resonant arcing (LC circuit). Im going to change the connection so that mains switch is before filtering PCB, not in the middle of it.
If you have a cap at the output of the amp this is normal.
Obviously annoying though.
It's probably possible to reduce the problem
Obviously annoying though.
It's probably possible to reduce the problem
I used to run a mobile disco and it popped when I turned off mains to record deck motors.
A 100nf mains rated voltage capacitor across switch contacts fixed it.
A 100nf mains rated voltage capacitor across switch contacts fixed it.